AutoEngCalc - Engineering Calculators

Surface Finish Conversion

Convert between Ra, Rz, Rt, RMS, CLA, N Grade and triangle symbols. Includes typical machining processes for each finish level.

Ra = 1.6 μm
N7 • △△△
Turning / Milling finish

Surface Roughness Conversion

Featured: Ra • Rz • RMS • N Grade • Triangle

Surface Finish Comparison

Ra values and typical processes

Conversion Relations
Rz ≈ 5.5 × Ra (average)
Rt ≈ 7–10 × Ra
RMS ≈ 1.11 × Ra
CLA = Ra

Enter value to see conversions

Surface Finish Guide

N Grades & Ra

N1: Ra 0.025 μm (mirror)

N6: Ra 0.8 μm (fine turning)

N7: Ra 1.6 μm (standard turning)

N9: Ra 6.3 μm (rough machining)

Triangle Symbols

△△△△: Ra ≤ 0.2 μm

△△△: Ra 0.4–0.8 μm

△△: Ra 1.6–3.2 μm

△: Ra 6.3–12.5 μm

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